Drivers: hv: kvp,vss: Fast propagation of userspace communication failure
If we fail to send a message to userspace daemon with cn_netlink_send()
there is no need to wait for userspace to reply as it is not going to
happen. This happens when kvp or vss daemon is stopped after a successful
handshake. Report HV_E_FAIL immediately and cancel the timeout job so
host won't receive two failures.
Use pr_warn() for VSS and pr_debug() for KVP deliberately as VSS request
are rare and result in a failed backup. KVP requests are much more frequent
after a successful handshake so avoid flooding logs. It would be nice to
have an ability to de-negotiate with the host in case userspace daemon gets
disconnected so we won't receive new requests. But I'm not sure it is
possible.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index 521c146..beb8105 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -350,6 +350,7 @@
__u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
__u32 val32;
__u64 val64;
+ int rc;
msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
if (!msg)
@@ -446,7 +447,13 @@
}
msg->len = sizeof(struct hv_kvp_msg);
- cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
+ rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
+ if (rc) {
+ pr_debug("KVP: failed to communicate to the daemon: %d\n", rc);
+ if (cancel_delayed_work_sync(&kvp_work))
+ kvp_respond_to_host(message, HV_E_FAIL);
+ }
+
kfree(msg);
return;